Devices for draining off oil from the valve cover and cooling the cylinder head of an internal combustion engine



W E. HENRY-BIABAUD 3,456,759

DEVICES FOR DRAINI NG OFF OIL FROM THE VALVE COVER AND COOLING THE CYLINDER HEAD OF AN INTERNAL COMBUSTION ENGINE 2 Sheets-Sheet 1 Filed March 28, 1966 f 2. N. ,2 in? 4 it 00 2 .G O l W M H g} 6 6. wk 2 y 19 E. HENRY-BIABAUD 3. 55.7 9

DEVICES FOR DRAINING OFF OIL FROM THE VALVE COVER AND COOLING THE CYLINDER HEAD OF AN INTERNAL COMBUSTION ENGINE Filed March 28, 1966 2 Sheets-Sheet 2 United States Patent 3,456,759 DEVICES FOR DRAINING OFF OIL FROM THE VALVE COVER AND COOLING THE CYLIN- DER HEAD OF AN INTERNAL COMBUSTION ENGINE Edmond Henry-Biabaud, Paris, France, assignor to Societe Anonyme Andre Citroen, Paris, France,

a French company Filed Mar. 28, 1966, Ser. No. 538,042 Claims priority, application France, Apr. 7, 1965, 12 259 Int. 01. F01m li/tio; F02b 75/24 US. Cl. 184-6 2 Claims ABSTRACT OF THE DISCLOSURE In internal combustion engines it is current practice to lubricate the valve rockers and valve shanks, and to cool the exhaust valve guides, by directing oil under pressure into the valve cover. However, evacuating this oil accumulated in the valve cover and likely to induce an excessive oil consumption constitutes a difficult problem.

It is the essential object of the present invention to provide a constructionally simple device or arrangement whereby the draining off of oil from the valve covers is facilitated while ensuring an efficient cooling of the hot central zone between the valves by means of an oil mist.

In this system utilizing the breather pipe connecting the crankcase to the atmosphere or the carburettor air intake and provided with a first pressurized chamber with oil and air return, this oil and air return from said first breather pipe chamber takes place through a plurality of relatively narrow ducts connecting the bottom of said first chamber of said breather pipe to the valve covers for draining off the oil from said valve covers and cool the hot portions of the cylinder head, which are specially designed for this purpose, by circulating an oil mist.

This system does not require the use of any special movable component element and is remarkable by its great constructional simplicity.

The features and advantages of this invention will appear more completely as the following description proceeds with reference to the accompanying drawing given by way of example and wherein:

FIGURE 1 illustrates an engine equipped with a breather pipe of known type;

FIGURE 2 illustrates the adaptation of the system of this invention to the engine of FIGURE 1 with a view to facilitate the draining off of the oil contained in the valve cover and the cooling of the cylinder head by means of an oil mist;

FIGURE 3 illustrates diagrammatically the cylinder head of a conventional air-cooled flat-twin engine;

FIGURE 4 illustrates in the same manner a cylinder head constructed according to this invention and adapted to be cooled by means of an oil mist.

In a flat-twin (or two-cylinder horizontal-opposed) engine, or in an engine constructed as an assembly of twocylinder units, or in a single-cylinder engine, the volume 3,456,759 Patented July 22, 1969 bounded by the two pistons 2 and 3 in the crankcase 4 containing the crankshaft 1 is subjected to an alternating variation. Since the crankcase is practically closed, alternating variations of the internal pressure in the crankcase 4 would take place on either side of the atmospheric pressure if no special provisions were made.

In fact, and for different reasons, such as atmospheric pollution or leakages, the average pressure in the crankcase 4 should constantly remain below the atmoshperic value.

In a US. Patent No. 3,229,591, the patentee proposed a device of the type illustrated in FIGURE 1.

Inthis breather pipe, a relatively large tube 6 interconnects a chamber 7 with the crankcase 4 through a cylindrical rubber valve '8 permit-ting the gaseous flow from the crankcase to the chamber while preventing the reverse flow. A second chamber 9 communicates with the first chamber 7 through the medium of a flat disc valve 10. This second chamber 9 communicates with the atmosphere, or, as shown, with the intake of carburettor 5. Finally, a pipe 11 of relatively small diameter which connects the first chamber 7 with the crankcase 4 and opens under the oil level in the sump directs into this crankcase the oil entrained in the tube 6 together with Thus, an alternating pressure having a mean value inferior to the atmospheric pressure prevails in crankcase 4, any excess pressure being relieved by opening the cylindrical valve 8.

In the first chamber 7 an over-pressure tending to open the fiat disc valve between this first chamber and the second chamber 9 is produced. The small quantity of oil deposited in the first chamber 7 is drained off to the bottom of crankcase 4 by this over-pressure.

This invention is applicable to a combustion engine equipped in the known manner as described hereinabove with reference to FIGURE 3.

To lubricate the valve rockers and valve shanks, and to cool the exhaust valve guides, it is a known practice to feed oil under pressure into the cylinder heads.

However, draining off this oil accumulating in the valve covers and likely to lead to an excessive oil consumption constitutes a difiicult problem.

It is the essential object of this invention to provide an arrangement facilitating the draining olf of the oil accumulating in the valve covers by taking advantage of the over-pressure produced in the first chamber 7. To this end, the relatively narrow pipe 11 of the known construction illustrated in FIGURE 1 is replaced by the two narrow pipes 11a of FIGURE 2 leading the oil and air from chamber 7 into the valve covers 12 wherefrom the oil is directed without delay to the bottom or sump of crankcase 4. This oil is drained oif through the tubes 13 enclosing the valve push-rods and through the holes 21 of valve tappets 22, with the complementary effect of improving the lubrication of the bearing faces of these tappets.

FIGURE 3 shows the cylinder head 14 of one of the engine cylinders, with the induction port 15 and the exhaust port 16, adapted to be cooled by means of an air flow circulating externally between the fins provided in portion 20. The cylinder head portion extending between the inlet valve 18 and the exhaust valve 19 is strongly heated due to the heat developing inside the cylinder head 14 and exhaust port 16. Moreover, dissipating this heat constitutes a ditficult problem owing to the relatively reduced cross-sectional area of the air passage 20 and to the relatively moderate surface area of the fins formed on the cylinder head. According to this invention, the cylinder-head cooling is improved by replacing the conventional circulation of external air by an internal circulation of oil mist or vapour delivered through the pipes 11a of FIGURE 2. The upper portion of cylinder head 14 which registers with the valve cover may be plain or provided either with fins 17 as shown in FIGURE 4, or with unevennesses of any desired and suitable configura tion in order to facilitate the heat transfer to the oil vapour or mist.

Although this invention has been described with specific reference to a preferred form of embodiment, it will be readily understood that many modifications and variations may be brought thereto without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim is:

1. An internal combustion engine comprising a crankshaft, a crankcase enclosing said crankshaft, cylinders opening into said crankcase on either side of said crankshaft, pistons slidably mounted in said cylinders and adapted to be reciprocated therein by being operatively connected to said crankshaft, cylinder heads closing said cylinders at their ends opposite to said crankshaft, at least two valves per cylinder, mounted on each cylinder head and having their shanks projecting from the external face of the relevant cylinder head, rockers mounted on said external face of each cylinder head for imparting a reciprocating motion to said valves, a valve cover secured to the external face of each cylinder head, rectilinear ducts connecting said valve cover to said crankcase through said cylinder head, rocker push-rods mounted with clearance in said ducts, each push-rod having one end projecting into said valve cover for oscillating said rockers and an opposite end projecting into said crankcase, a camshaft rotatably mounted in said crankcase and rotatably driven from said crankshaft for engaging said opposite ends of said rocker push-rods in order to impart reciprocating movement to said valves through said rockers, a breather for controlling the pressure in said crankcase, said breather having a first chamber disposed above said crankcase, a non-return valve connecting said chamber to the inner space of said crankcase, another chamber disposed above said first chamber and communicating with the surrounding atmosphere, and another non-return valve connecting said first chamber to said other chamber, and relatively narrow duct means each adapted to connect said first breather chamber to the valve cover of each cylinder.

2. An internal combustion engine equipped as set forth in claim 1, wherein said relatively narrow duct means adapted to connect said first breather chamber to the valve cover of each cylinder, and said rectilinear ducts provided through each cylinder head for the passage of said rocker push-rods with clearance, are disposed with a descending slope.

References Cited UNITED STATES PATENTS 1,354,663 10/ 1920 Kirkman et al. 1,408,179 2/1922 Du Pont. 1,429,014 9/ 1922 Blanchard. 1,529,240 3/ 1925 Chesnutt. 1,876,160 9/ 1932 Zahodiakin. 2,111,242 3/1938 Harley. 2,381,339 8/1945 Doman. 2,902,022 9/1959 Bakke et al.

HOUSTON S. BELL, 111., Primary Examiner US. Cl. X.R. 

